The National Social Life, Health and Aging Project (NSHAP) is a longitudinal study of older adults designed to examine the mechanisms by which social factors-such as intimate relationships and social networks-affect and are affected by health. In 2005-06, questionnaire and biomeasure data were collected from a nationally- representative sample of 3,005 community-dwelling adults ages 57-85 (W1). These referent respondents were reinterviewed in 2010-11, together with coresident spouses/partners (W2). A third wave (W3), to be collected in 2015-16, will reinterview all surviving referent respondents and W2 spouses/partners. Collectively, NSHAP's W1, W2 and W3 provide extensive, longitudinal, health and social information for a nationally representative sample of older adults. We aim to add a new cohort to the NSHAP sample to capture the unique and epidemiologically intriguing Baby Boom cohort. Funding for refreshing the sample with a new cohort of aging Baby Boomers (i.e., respondents born from 1948 through 1965) will substantially increase the value of NSHAP for various research communities, opening up key avenues for conducting innovative and effective health related research, such as: (1) comparing the social connections, networks, environment and relationships of older adults in different birth cohorts and the relationship of these social factors with health; (2) tracing cohort differences in the life courseof cohabitations and marital relationships; (3) comparing trajectories of physical function, self-rate health, health behaviors, prevalence of chronic diseases, and physiological functioning across ages over birth cohorts; (4) tracking the transition from middle-age to older ages; and (5) capturing racial and ethnic differences in the ages at which relevant chronic conditions become prevalent across cohorts. Funding will support adding over 2,500 respondents. The addition of respondents ages 50 to 67 in 2015- 16 will provide a nationally-representative, high-quality data set on social relationships and health for ages 50 to 95, setting the stage for a sequential cohort design. The addition of the Baby Boom cohort will allow researchers to compare health and social outcomes along age, period, and cohort axes. We will harmonize data collection with W3 of NSHAP to form a single, cohesive dataset, including in-home interviews with 1,600 new respondents born between 1948-1965 and their spouses or co-residential romantic partners (n=900). This will yield extensive, nationally representative, self-reported and biomeasure data on multiple cohorts' physical and mental health, physical and cognitive functioning, medication use, and pathways of health and mortality within social contexts, facilitating comparative assessments of health disparities between gender, race, ethnicity and socio- economic status by age within and across cohorts.